Crushing and Washing The 'four washings and three crushings' production process represents the highest level of refined salt produced by the Chinese crushing method, of which four washes are: â??â??One-stage spiral washing â??â??Secondary spiral washing â??â??Vertical mixing and washing - countercurrent washing Three powder is: - primary crush - wet crushing - dry crushing Through the reasonable combination of wet pulverization and dry pulverization, various washing methods are matched to each other to ensure that the product salt reaches a high quality.